Fermentation of beet molasses



Patented Feb. 1, 1938 I 2.107.261 i FERMENTATION F BEET MOLASSES David A. Legg, Terre Haute, and Noble B. Tarvin, Brazil, Ind., assignors to Commercial Solvents Corporation, Terre Haute, Ind., a corporation of Maryland No Drawing. Application July 30, 1934, a Serial No. 737,574

9 Claims.

The present invention relates to the production of valuable products by the fermentation of beet molasses. More particularly, this invention re,- lates to the butyl alcohol fermentation of beet molasses by means of bacteria of the general type Clostridium saccharo-acetolmtgylicum.

The fermentation of soluble carbohydrate mashes, in general, by means of bacteria of the group Clostridium saccharo-acetobutylicum has been disclosed in copending application U. S. Ser. No. 675,459 by J. C. Woodrufi, D. A. Legg, and H. R. Stiles, filed June 12, 1933. According to the process of this application, soluble carbohydrate mashes, such as cane molasses mashes, containing ammonia nitrogen and preferably, also, degraded protein nitrogen, are fermented while controlling the acidity of the mash by the addition of alkaline neutralizing agents whereby the final hydrogen ion concentration falls within the range pH 5.0 to pH- 6.2. This process gives very satisfactory yields with most soluble carbohydrate mashes,-but we have found that in the case of beet molasses mashes the yields are unsatisfactorily low, in most cases, sufficiently so to make the process impractical from a commercial standpoint.

In view of the unusually high nitrogenous content of beet molasses (from 4 to 5 times that of cane molasses) it was thought that an excessive concentration of nitrogenous materials might be responsible for the decreased yield. The elimination of the additional ammonia nitrogen of U. S.

Ser. No..675,459 succeeded in increasing the yield teinaceous materials from grain alcohol distillery slop. When employing this type ,of nitrogenous material, according to the process outlined herein, we have been able to secure yields greater than what are thought to be the theoretical values, based on the sugar content of-the mashes. This indicates that carbohydrates other than sugars are fermented to some extent and that the beet molasses is therefore utilized to greater commercial advantage than in any previously known fermentation process.

seen to include both the soluble and insoluble' forms of nitrogen in the slop. We believe the insoluble form of nitrogen in this material to be the most advantageous, but in.general we prefer to utilize both forms of nitrogen by employing whole slop as the supplementary nutrient. This procedure is advantageous from an economical standpoint and the slop may readily be incorporated into the mash by substituting it for a portion of the water.

The grain distillery slops suitable for our process may be those from the malt process, the amylo process, or the acid hydrolysis process. The malt process is exemplified by the common procedure of saccharifying a cereal mash by means of barley malt and the acid hydrolysis process is exemplified by the common procedure of saccharifying such a mash by means of a mineral acid. The amylo process involves saccharification by means of organisms such as Amyloces rouxii, mucor or Rhizopus delemar as described in the article on this process in Indus trial and Engineering Chemistry, 25, 87-89, (1933). The ash content of the slop from the acid hydrolysis process will be found to be considerably higher than that in the other cases owing to the amount of alkali utilized for the neutralization of the mineral acid. However, except in the case of certain samples of beet molasses which have a particularly high alkali content, the ash content of the slop will not necessarily be sufficient to undesirably efiect the present process. In general, we prefer to.utilize the slop from the malt process since the proportion of unchanged proteins tends to be somewhat higher in this case.-

The amount of distillery slop to be added in any fermentation will,of course, depend upon the concentration and state of degradation of the other nitrogenous material present in the mash. For example, a mash containing substantial amounts of cane molasses or other materials containing substantial concentrations of complex nitroge nous matter will require less additional nitrogenous nutrient than one in which beet molasses comprises substantially all of the fermentable carbohydrate. However, in general it may be said that from 5-50% by volume of whole slop or its equivalent of other forms of proteinaceous material derived from the whole slop will usually be found to be satisfactory. From 10-20% by volume will generally be found to be preferable and may advantageously be employed in any mash containing beet molasses as a major source.

of carbohydrate. In any case, the lower economical limit of slop concentration may easily be determined by preliminary fermentations.

when employing grain alcohol distillery slop asthe supplementary nutrient for this fermentation no additional nitrogenous materials need ganisms must be satisfied according to the usual practice in fermentations of this type. For example. if the particular samples of beet molasses and distillery slop do not furnish sufficient phosphates-or other mineral nutrients; these materials should be added in the requisite amounts.

An important aspect of the fermentation of beet molasses mashes comprises the acidity con trol during the fermentation. We have found that the organisms of the type Clostridium saccharo-acetobuiylzcum generally require a more alkaline reaction for the fermentation of beet molasses mashes than for the fermentation of other soluble carbohydrate mashes. In copending application U. S. Ser. No. 675,459 it is stated that for the usual type of soluble carbohydrate mash the acidity should be controlled so that the final hydrogen ion concentration falls within the range pH 5.0 to pH 6.2. However, we have found that for mashes containing beet molasses as a major component the acidity of the fermenting -mash should be maintained at a value such that the final hydrogen ion concentration falls within the range pH 5.5 to 7.0 and preferably within the range pH 5.7 to 6.5.

The usual types of beet molasses will be found to contain considerable quantities of alkaline buffering materials and to have an initial alkaline reaction ranging from pH 7.0 to pH 9.0. This degree of alkalinity is usually insufiicient to adversely affect the fermentation, and the mashes may be inoculated at their orginal hydrogen ion concentration without the necessity for neutralizing. In fact, we have found that it is generally undesirable to attempt to neutralize the mashes with strong acids such as mineral acids. However, the acidity of the grain alcohol distillery slops, which is believed to be due to the presence of organic acids, is insufficient to adversely affect the fermentation, and these materials may usually be added directly without neutralization.

The alkaline buffering capacity of most types of beet molasses will be found to be sufiicient to maintain the acidity within the necessary limits to secure the desired final hydrogen ion concentration. This will generally be true even though a considerable amount of organic'acid is added in the grain distillery slop. However, in the case of samples of beet molasses which are deficient in buffering materials, or in case an unduly acid slop is employed, the acidity of the fermenting mash may be controlled by any of the methods disclosed in copending application Ser. No.

675,459. For example, the fermentation may be continuously or semi-continuously neutralized with soluble alkalies, or an insoluble alkaline material may be incorporated into the mash before inoculation. In any case, the necessity for the use of alkaline neutralizing materials and the amounts necessary for optimum yield may readlly be determined by preliminary fermentations.

The organisms which are suitable for use in our process are the bacteria of the group Clostridium saccharo-acetobutylicum, which are described at length in copending application U. S. Ser. No. 675,459, referred to above. Our process is particularly adapted to fermentations by means Example I A sterile mash containing approximately 10% of Wisconsin beet molasses (5.10% sugar) and containing 16.3% by volume of grain alcohol distillery slop was inoculated with an actively fermenting culture of Clostridium saccharo-acetobutylicum oz and incubated at 30 C. for 68 hours. The yield and solvent ratio were found to be as follows:

Yield Solvent ratio Grams solvents per liter Percent of total sugar Butyl Ethyl alcohol Antone alcohol A control fermentation containing no distillery slop gave a yield of only 8.1% of the total sugar.

Example II A sterile mash containing approximately 10% of Ohio beet molasses (4.82% total sugar) and containing 6.4% by volume of grain alcohol distillery slop was inoculated with an. actively fermenting culture of Clostridium saccharo-acetobutylicum' 0c and incubated-at 30 C. for 68 hours.

-The yield and solvent ratio were-found to be as follows Yield Solvent ratio Grams solvents per liter Ethyl alcohol Percent of Butyl total sugar alcohol Acetone The control fermentation in this case gave a yield of 18.8% of the total sugar.

Example III A sterile mash containing approximately 10% of Michigan beet molasses (4.98% total sugar), 12.6% by. volume grain alcohol distillery slop, and 0.1%- by weight of (NH4)2HPO4 was inoculated with an actively fermenting culture of Clostridz'um saccharo-acetobutylicum a and incubated at 30 C. for 68 hours. The yield and solvent ratio were found to be as follows:

Yield Solvent ratio Grams solvents per liter Percent of Bntyl total sugar Ethyl alcohol Acetone alcohol as 4 19. 1 11. 4 a. 2

The control fermentation, containing the small amount of phosphate but no distillery slop, gave a yield of 30.0% of the total sugar.

Yield Solvent ratio Grams solvents per liter roroollt of ,Butyl Ethyl :3 alcohol alcohol The control experiment containing the same amount of calcium carbonate but no distillery slop gave a yield of 20.6% of the total sugar.

trample V A sterile mash containing approximately 10% of Ohio beet molasses (4.82% total sugar), 12.3% by volume of grain alcohol distillery slop, and 0.1% by weight of KaHPOq. was inoculated with an actively fermenting culture of Clostridium aaccharo acetobutylicum a and incubated at 30 C. for 68 hours. The yield and solvent ratio were found to be as follows:

Yield Solvent ratio Percent of Grams total solvents 335 sugar per liter Ethyl alcohol The control fermentation, containing the small amount of phosphate but no distillery slop, had a yield of 28.4% of the total sugar.

. Example v1 A sterile mash containing 5.06% total sugar (50% Michigan beet molasses-50% hydrol), 16.3% by volume grain alcohol distillery slop. and 0.07% by weight of (N34) :HPOl was inoculated with an actively fermenting: culture of Clostridium saccharo-acetobutulicum a and incubated at 30 C. for 68 hours. The yield and solvent ratio were found to be as follows:

Yield Solvent ratio Grams solvents per liter Percent of total sugar Bntyl Ethyl alcohol alcohol plicable, generally, to soluble carbohydrate mashes containing beet molasses as a major component, irrespective of the remaining carbohydrate content. Likewise, it will be apparent to those skilled in the art that various modifications of procedure may be employed without departing from the scope, of our invention. For example, if a mixed mash is to be employed, such as the mixed hydrol-beet molasses mash of Example V, the fermentation could suitably be started in the molasses mash and the hydrol-distillery slop solution added to this mash after fermentation had become sufliciently active. The applicability of the various modifications of procedure disclosed in copending application Ser. No. 675,459 will likewise be apparent to one skilled in the art. In general, it may be said that any such modifications or the use of any equivalents which would naturally occur to a skilled hacteriologist or fermentation chemist, may be employed without departing from the scope of our invention.

Our invention now having been described, what we claim is:

.1. In the fermentation of an essentially solu-' ble carbohydrate mash containing beet molasses as a major component, by means of bacteria of the group Clostridium saccharo-ucetobutylicum, the step which comprises effecting the fermentation in a mash containing proteinaceous material from grain alcohol distillery slop.

2. In the fermentation of an essentially soluble carbohydrate mash containing beet molasses as a major component, by means of bacteria of the group C'lostridium saccharo-acetobutylicum, the step which comprises effecting the fermentation in a mash containing proteinaceous material from grain alcohol distillery slop equivalent to from 540% by volume of whole slop.

3. In the fermentation of an essentially soluble carbohydrate mash containing beet molasses as a major component, by means of bacteria of the group Clostridium saccharo-acetobutylicum, the step which comprises effecting the fermentation in a mash containing from 10-20% of grain alcohol distillery slop. 7

4. In the fermentation of an essentially soluble carbohydrate mash containing beet molasses as a major component, by means of bacteria of the group clostridium saecharo-acetobutylicum, the step which comprises effecting the fermentation in a mash containing proteinaceous material from grain alcohol distillery slop, and maintaining the acidity of the fermenting mash at a value such that the final hydrogen ion concentration falls within the range pH 5.5 to 7.0.

5. In the fermentation of an essentially soluble carbohydrate mash containing beet molasses as a major component, by means of bacteria of the group C'lostridium saccharo-acetobutylicum, the step which comprises eflecting the fermentation in a mash containing proteinaceous material from grain alcohol distillery slop equivalent to from -50% by volume of whole slop, and maintaining the acidity of the fermenting mash at a value such that the final hydrogen ion concentration falls .within the range pH 5.5 to 7.0.

6. In the fermentation of an essentially soluble carbohydrate mash containing beet molassesas a major component, by means of bacteria of the group Clostridium saccharo-acetobutylicum, the step which comprises effecting the fermentation in a mash containing from 1020% of grain alcohol distillery slop, and maintaining the acidity of the fermenting mash at a value such that the final hydrogen ion concentration falls within the range pH 5.5 to 7.0.

'7. In the fermentation of an essentially soluble carbohydrate mash containing beet molasses as a major component, by means of bacteria of the group Clostridiu-m saccharo-acetobutylicum, the step which comprises effecting the fermentation in a mash containing proteinaceous material from grain alcohol distillery slop, and maintaining the acidity of the fermenting mash at a value such that the final hydrogen ion concentration falls within the range pH 5.7 to 6.5.

8. In the fermentation of an essentially soluble carbohydrate mash containing beet molasses as a major component, by means of bacteria of the group Clostridium saccham-aceto-butylicum, the step which comprises effecting the fermentation in a mash containing proteinaceous material from grain alcohol distillery slop equivalent to from 5-50% .by volume of whole slop, and maintaining the acidity of the fermenting mash at a Value such that the final hydrogen ion concentration falls within the range pH 5.7 to 6.5.

9. In the fermentation of an essentially soluble carbohydrate mash containing beet molassesas a. major component, by means of bacteria of the group Clostridium saccharo-acetobutylicum, the step which comprises efiecting the fermentation in a mash containing from 10 20% of grain alcohol distillery slop, and maintaining the acidity of the fermenting mash at a value such that the final hydrogen ion concentration falls within the range 5.7 to 6.5.

DAVID A. LEGG. NOBLE R. TARVIN.

Certificate of Correction Patent No. 2,107,261.

February 1, 1938.

DAVID A. LEGG ET ALI It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 2, second column, line 6, for the Greek letter a (alpha) read 7 (gamma); and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Office' Signed and sealed this 12th day of April, A. D. 1938.

[SEAL] Acting Commissioner of Patents.

hydrogen ion concentration falls within the range pH 5.5 to 7.0.

'7. In the fermentation of an essentially soluble carbohydrate mash containing beet molasses as a major component, by means of bacteria of the group Clostridiu-m saccharo-acetobutylicum, the step which comprises effecting the fermentation in a mash containing proteinaceous material from grain alcohol distillery slop, and maintaining the acidity of the fermenting mash at a value such that the final hydrogen ion concentration falls within the range pH 5.7 to 6.5.

8. In the fermentation of an essentially soluble carbohydrate mash containing beet molasses as a major component, by means of bacteria of the group Clostridium saccham-aceto-butylicum, the step which comprises effecting the fermentation in a mash containing proteinaceous material from grain alcohol distillery slop equivalent to from 5-50% .by volume of whole slop, and maintaining the acidity of the fermenting mash at a Value such that the final hydrogen ion concentration falls within the range pH 5.7 to 6.5.

9. In the fermentation of an essentially soluble carbohydrate mash containing beet molassesas a. major component, by means of bacteria of the group Clostridium saccharo-acetobutylicum, the step which comprises efiecting the fermentation in a mash containing from 10 20% of grain alcohol distillery slop, and maintaining the acidity of the fermenting mash at a value such that the final hydrogen ion concentration falls within the range 5.7 to 6.5.

DAVID A. LEGG. NOBLE R. TARVIN.

Certificate of Correction Patent No. 2,107,261.

February 1, 1938.

DAVID A. LEGG ET ALI It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 2, second column, line 6, for the Greek letter a (alpha) read 7 (gamma); and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Office' Signed and sealed this 12th day of April, A. D. 1938.

[SEAL] Acting Commissioner of Patents. 

